Detent mechanisms 10 of the prior art, as best shown in FIG. 1, include a coil-spring 14 biasing a spherical steel ball 15. The ball 15 is slideable in a race 13 formed into a housing 11 to positively locate the ball 15 into one of a series of adjacent groves 16 that are formed in a base 12. The bias provided by the spring 14 ensures that the ball 15 cannot be moved to the next adjacent groove 16 until a predetermined level of force or torque is provided, upon which, the ball 15 will snap into the next adjacent groove 16. Since the ball 15 will only come to rest in a groove 16, a ratchet or detent mechanism is provided whereby the position of the housing 11 may be adjusted relative to the base 12 in finite increments. Such devices are currently available on chairs to allow the chair arm to be adjusted in increments relative to its support base. An example of a rotary detent mechanism employing a similar mechanical elements can be found in FIG. 4 of U.S. Pat. No. 2,909,047 to Walterschied-Muller et al entitled "Overload Clutch."
Although these mechanical detent mechanisms 10 provide an effective incremental detent function, they tend to be noisy and have an undesirable very rigid and mechanical feel. For example, when such devices are implemented in repositionable arms of office chairs, the clicking noise resulting from adjustments is an annoyance.
U.S. Pat. No. 4,004,506 to McInerny entitled "Endorser Drum Having Indexable Self-Aligning Print Wheels" describes an annular-shaped elastomer print wheel 10 having a plurality of grooves 14 and a pin 16 having a plurality of splines 18 which engage therewith. Upon application of a torque to the print wheel, the splines 18 will snap into adjacent ones of the grooves 14. However, the '506 McInerny device cannot carry axial loads, thus it is ineffective in bushing applications. Accordingly, there has been a long felt, and unmet, need for a smooth and quite detent mechanism capable of providing a fine incremental detent function and which is capable of carrying axial loads.